The U.S. postal regulations make a distinction between Postal Cards and post cards. A Postal Card is supplied by the Postal Service with a postage stamp printed or impressed on it. A post card is a privately printed mailing card of any light color which does not prevent legible addresses and postmarks from being placed thereon; brilliant colors are not permitted.
To qualify for mailing/handling at the First-Class card rate, the post cards must be: (a) not smaller than 3.5 inches by 5 inches, nor larger than (currently) 4.25 inches by 6 inches;
(b) rectangular in shape and of approximately the same form, quality and weight as postal cards (the weight basis is presently 125 grams per square meter);
(c) made of a piece of unfolded and uncreased paper or card stock of approximately the quality and weight as postal cards;
(d) of uniform thickness not less than 0.007 inch thick or greater than 0.0095 inch thick.
There are other regulations and restrictions regarding "double post cards" but these are not per se relevant to the present invention because such a double post card consists of two cards fitting the foregoing regulatings, one of which may be detached by the recipient and returned as a reply. Each card must have postage affixed, and must be secured in folded relation such that the inner folds of the cards ca be examined. Thus, a conventional double post card by definition cannot per se conceal confidential indicia, although the sending card (not the reply card) of a double post card can be prepared according to this invention to send confidential data.
It should be noted that post cards may be as large as 6 inches by 10 inches, although beyond the 4.5 inch by 6 inch size, the same postage is required as for a First Class letter. In some cases, the savings in materials, simplicity of recording/handling of information, and generally handling, may be attractive even without the ability to use the post card postage rates.
Post cards bearing "attachments" are not mailable at the rates for postal cards or post cards. However, labels affixed by adhesive for the purpose of showing the address and the return address are permitted. Thus, such labels if used according to the regulations can have an additional function of concealing confidential indicia.
Various proposals have been made for placing confidential data and/or indicia on post cards, and covering the confidential information with labels, laminates, or other means. The most notable of such prior art is U.S. Pat. No. 4,278,199, which teaches placing confidential information on either the face or the reverse side of a post card, and covering that information with an opaque removable label. However, that patent does not teach the use of an address label for this purpose, but instead uses a label which is plain or marked in some other way. This is not (and has not been) permissible under U.S. Postal Service regulations, since such a label is in effect a laminate not allowed within the post card requirements, and the resulting card/label combination cannot qualify for the reduced postage rate applicable to properly designed and used post cards. Thus, proposals of that tupe have only limited utility under U.S. Postal regulations.
In addition, of significant importance, U.S. Pat. No. 4,278,199 makes no reference to maintaining label security, yet this is quite important to the sender and recipient; the patent is limited to covering no more than half the card area; and there is no recognition of the desirability to adapt to automated handling and reading (in particular the addressee (recipient) addresses).